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<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX This file is generated from xml source: DO NOT EDIT XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX --><title>Security Tips - Apache HTTP Server</title><link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /><link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /><link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link href="../images/favicon.ico" rel="shortcut icon" /></head><body id="manual-page"><div id="page-header"><p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p><p class="apache">Apache HTTP Server Version 2.0</p><img alt="" src="../images/feather.gif" /></div><div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div><div id="path"><a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.0</a> > <a href="./">Miscellaneous Documentation</a></div><div id="page-content"><div id="preamble"><h1>Security Tips</h1><div class="toplang"><p><span>Available Languages: </span><a href="../en/misc/security_tips.html" title="English"> en </a> |<a href="../ko/misc/security_tips.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p></div> <p>Some hints and tips on security issues in setting up a web server. Some of the suggestions will be general, others specific to Apache.</p> </div><div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#uptodate">Keep up to Date</a></li><li><img alt="" src="../images/down.gif" /> <a href="#serverroot">Permissions on ServerRoot Directories</a></li><li><img alt="" src="../images/down.gif" /> <a href="#ssi">Server Side Includes</a></li><li><img alt="" src="../images/down.gif" /> <a href="#cgi">CGI in General</a></li><li><img alt="" src="../images/down.gif" /> <a href="#nsaliasedcgi">Non Script Aliased CGI</a></li><li><img alt="" src="../images/down.gif" /> <a href="#saliasedcgi">Script Aliased CGI</a></li><li><img alt="" src="../images/down.gif" /> <a href="#dynamic">Other sources of dynamic content</a></li><li><img alt="" src="../images/down.gif" /> <a href="#systemsettings">Protecting System Settings</a></li><li><img alt="" src="../images/down.gif" /> <a href="#protectserverfiles">Protect Server Files by Default</a></li><li><img alt="" src="../images/down.gif" /> <a href="#watchyourlogs">Watching Your Logs</a></li></ul></div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="section"><h2><a name="uptodate" id="uptodate">Keep up to Date</a></h2> <p>The Apache HTTP Server has a good record for security and a developer community highly concerned about security issues. But it is inevitable that some problems -- small or large -- will be discovered in software after it is released. For this reason, it is crucial to keep aware of updates to the software. If you have obtained your version of the HTTP Server directly from Apache, we highly recommend you subscribe to the <a href="http://httpd.apache.org/lists.html#http-announce">Apache HTTP Server Announcements List</a> where you can keep informed of new releases and security updates. Similar services are available from most third-party distributors of Apache software.</p> <p>Of course, most times that a web server is compromised, it is not because of problems in the HTTP Server code. Rather, it comes from problems in add-on code, CGI scripts, or the underlying Operating System. You must therefore stay aware of problems and updates with all the software on your system.</p> </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="section"><h2><a name="serverroot" id="serverroot">Permissions on ServerRoot Directories</a></h2> <p>In typical operation, Apache is started by the root user, and it switches to the user defined by the <code class="directive"><a href="../mod/mpm_common.html#user">User</a></code> directive to serve hits. As is the case with any command that root executes, you must take care that it is protected from modification by non-root users. Not only must the files themselves be writeable only by root, but so must the directories, and parents of all directories. For example, if you choose to place ServerRoot in /usr/local/apache then it is suggested that you create that directory as root, with commands like these:</p> <div class="example"><p><code> mkdir /usr/local/apache <br /> cd /usr/local/apache <br /> mkdir bin conf logs <br /> chown 0 . bin conf logs <br /> chgrp 0 . bin conf logs <br /> chmod 755 . bin conf logs </code></p></div> <p>It is assumed that /, /usr, and /usr/local are only modifiable by root. When you install the <code class="program"><a href="../programs/httpd.html">httpd</a></code> executable, you should ensure that it is similarly protected:</p> <div class="example"><p><code> cp httpd /usr/local/apache/bin <br /> chown 0 /usr/local/apache/bin/httpd <br /> chgrp 0 /usr/local/apache/bin/httpd <br /> chmod 511 /usr/local/apache/bin/httpd </code></p></div> <p>You can create an htdocs subdirectory which is modifiable by other users -- since root never executes any files out of there, and shouldn't be creating files in there.</p> <p>If you allow non-root users to modify any files that root either executes or writes on then you open your system to root compromises. For example, someone could replace the <code class="program"><a href="../programs/httpd.html">httpd</a></code> binary so that the next time you start it, it will execute some arbitrary code. If the logs directory is writeable (by a non-root user), someone could replace a log file with a symlink to some other system file, and then root might overwrite that file with arbitrary data. If the log files themselves are writeable (by a non-root user), then someone may be able to overwrite the log itself with bogus data.</p> </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="section"><h2><a name="ssi" id="ssi">Server Side Includes</a></h2> <p>Server Side Includes (SSI) present a server administrator with several potential security risks.</p> <p>The first risk is the increased load on the server. All SSI-enabled files have to be parsed by Apache, whether or not there are any SSI directives included within the files. While this load increase is minor, in a shared server environment it can become significant.</p> <p>SSI files also pose the same risks that are associated with CGI scripts in general. Using the "exec cmd" element, SSI-enabled files can execute any CGI script or program under the permissions of the user and group Apache runs as, as configured in httpd.conf.</p> <p>There are ways to enhance the security of SSI files while still taking advantage of the benefits they provide.</p> <p>To isolate the damage a wayward SSI file can cause, a server administrator can enable <a href="../suexec.html">suexec</a> as described in the <a href="#cgi">CGI in General</a> section.</p> <p>Enabling SSI for files with .html or .htm extensions can be dangerous. This is especially true in a shared, or high traffic, server environment. SSI-enabled files should have a separate extension, such as the conventional .shtml. This helps keep server load at a minimum and allows for easier management of risk.</p> <p>Another solution is to disable the ability to run scripts and programs from SSI pages. To do this replace <code>Includes</code> with <code>IncludesNOEXEC</code> in the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive. Note that users may still use <--#include virtual="..." --> to execute CGI scripts if these scripts are in directories designated by a <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code> directive.</p> </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="section"><h2><a name="cgi" id="cgi">CGI in General</a></h2> <p>First of all, you always have to remember that you must trust the writers of the CGI scripts/programs or your ability to spot potential security holes in CGI, whether they were deliberate or accidental. CGI scripts can run essentially arbitrary commands on your system with the permissions of the web server user and can therefore be extremely dangerous if they are not carefully checked.</p> <p>All the CGI scripts will run as the same user, so they have potential to conflict (accidentally or deliberately) with other scripts e.g. User A hates User B, so he writes a script to trash User B's CGI database. One program which can be used to allow scripts to run as different users is <a href="../suexec.html">suEXEC</a> which is included with Apache as of 1.2 and is called from special hooks in the Apache server code. Another popular way of doing this is with <a href="http://cgiwrap.unixtools.org/">CGIWrap</a>.</p> </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div><div class="section"><h2><a name="nsaliasedcgi" id="nsaliasedcgi">Non Script Aliased CGI</a></h2> ⌨️ 快捷键说明
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